To find the equation that shows when the two popcorn machines will have the same amount of popcorn left, we start by expressing the amount of popcorn left for each theatre in terms of the variable \( x \), which represents the number of hours passed.
For Movie Theatre A:
- Initial capacity: 100 gallons
- Sells 3 gallons per hour
- Amount left after \( x \) hours: \( 100 - 3x \)
For Movie Theatre B:
- Initial capacity: 150 gallons
- Sells 5 gallons per hour
- Amount left after \( x \) hours: \( 150 - 5x \)
We set the two expressions equal to each other to find when they will have the same amount of popcorn left:
\[ 100 - 3x = 150 - 5x \]
This is the correct equation that represents when the two popcorn machines will have the same amount of popcorn left.